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Discussion Starter · #1 · (Edited)
Hi guys, i'm hoping you can help me learn what went wrong here. It seems I lean/burnt my motor down but I don't understand exactly how. Sorry for the long initial post here but i wanted to give you as much info. as possible from the gitgo. The subject is a prof. built 540" bbc, prof. ported iron heads, dual hp750 carbs on a edelbrock tr-2 tunnel ram, 10:1 pump gas deal with Basset twisty headers,(runin dry) that has run flawless for the last 3 years since it was rebuilt and right up until the moment it broke the #3 valve and piston. This motor was dyno'd on Shell 92 octane pump gas @ 673 hp @ 5800 rpm (for example) . I run it on at least 100 octane unleaded pump gas that I get @ Terrible Herbst gas station in Parker. (I run in the shalows of the big river area since the powers that be have decided we don't need water to boat. ) The pump has indicated both vp fuels and sonoco fuels in the past 2 years. Occaisionally I'll add up 20% leaded 112 octain race gas from Parker Oil (vp fuels i believe) when i fill my 55 gal. drum for conveinence. The only thing i did differently from the day/days before was added approx. 20% of my fuel volumn in the boat from the affore mentioned drum which had only about 10 gals remaining in it from last summer. I realize this may seem to be the obvious culprit at this point to the more knowledgeful peeps which is why I am here asking, but I just want to verify and learn as much as possible from this costly situation.:)st:|err Before adding the old gas I inspected it by smell, color and clarity. The smell seemed fine compared to new gas, the color was considerably darker (caramel colored like new castle beer in a bottle) and of concerne, (unfortunately not enough to just say oh hell no lol):)coffee and clean of any debris etc. The gas in the boat was all recent/new gas and consisted of mostly ul. 100 octain and a little remaining 110 from the Elsinore race in may. I was about 30 minutes into a cruise up river with wifey, running about 3500 rpm when the motor began to sound just slightly pitchy and caught my ear. With that I began to back off the loud padal slightly to see if the tone would change, no change. As I started to ease back into the loud padal the rpm began to slow and then pow, #3 exhaust valve/piston contact occured. (that's a gutwrenching sound) I quickly hit the kill and coasted to a stop, looked at all my gauges and paddled to shore. All operating temps were normal, water temp at intake manifold(location guage) was 170*, oil temp 180* (elec. ga.) oil pres. 60psi (mech. ga.) Here's some pictures of the spark plugs for your veiwing pleasure before i got home and began to look into it. The first 2 pic is #1,3,5,7 from l-r. The second 2 are 2,4,6,8 from l-r. Apparently #6 sucked up the majority of the oil and some debris from the piston head. More pics of internal carnage to follow in next post.
 

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E-7 Sheepdog (ret)
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if anything imo that mill was to fat(rich)according to the plugs you pulled.

that sucks,best wishes:D
Agreed, rich is anything, certainly not lean.

I think more along the lines of you simply busted a valve, not lean-detonated the motor.
Now, anything can happen, but, I've seen very few folks lean-out an engine to death and break a valve from it.
Melt holes in pistons, sure, all the time, melt off ring land tops too, but the steel valves tolerate more heat than Al. pistons.

As to why the valve broke, who knows. Maybe got tight and hung up, smacked by the piston, maybe had a microscopic imperfection for a stress riser, maybe sub-surface in the alloy, maybe shock from harmonics, maybe it just broke.
Hard to think it got wet when hot and crystalized running dry headers.
 

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mo balls than $cents$
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Hi guys, i'm hoping you can help me learn what went wrong here. It seems I lean/burnt my motor down but I don't understand exactly how. Sorry for the long initial post here but i wanted to give you as much info. as possible from the gitgo. The subject is a prof. built 540" bbc, prof. ported iron heads, dual hp750 carbs on a edelbrock tr-2 tunnel ram, 10:1 pump gas deal with Basset twisty headers,(runin dry) that has run flawless for the last 3 years since it was rebuilt and right up until the moment it broke the #3 valve and piston. This motor was dyno'd on Shell 92 octane pump gas @ 673 hp @ 5800 rpm (for example) . I run it on at least 100 octane unleaded pump gas that I get @ Terrible Herbst gas station in Parker. (I run in the shalows of the big river area since the powers that be have decided we don't need water to boat. ) The pump has indicated both vp fuels and sonoco fuels in the past 2 years. Occaisionally I'll add up 20% leaded 112 octain race gas from Parker Oil (vp fuels i believe) when i fill my 55 gal. drum for conveinence. The only thing i did differently from the day/days before was added approx. 20% of my fuel volumn in the boat from the affore mentioned drum which had only about 10 gals remaining in it from last summer. I realize this may seem to be the obvious culprit at this point to the more knowledgeful peeps which is why I am here asking, but I just want to verify and learn as much as possible from this costly situation.:)st:|err Before adding the old gas I inspected it by smell, color and clarity. The smell seemed fine compared to new gas, the color was considerably darker (caramel colored like new castle beer in a bottle) and of concerne, (unfortunately not enough to just say oh hell no lol):)coffee and clean of any debris etc. The gas in the boat was all recent/new gas and consisted of mostly ul. 100 octain and a little remaining 110 from the Elsinore race in may. I was about 30 minutes into a cruise up river with wifey, running about 3500 rpm when the motor began to sound just slightly pitchy and caught my ear. With that I began to back off the loud padal slightly to see if the tone would change, no change. As I started to ease back into the loud padal the rpm began to slow and then pow, #3 valve/piston contact occured. (that's a gutwrenching sound) I quickly hit the kill and coasted to a stop, looked at all my gauges and paddled to shore. All operating temps were normal, water temp at intake manifold(location guage) was 170*, oil temp 180* (elec. ga.) oil pres. 60psi (mech. ga.) Here's some pictures of the spark plugs for your veiwing pleasure before i got home and began to look into it. The first 2 pic is #1,3,5,7 from l-r. The second 2 are 2,4,6,8 from l-r. Apparently #6 sucked up the majority of the oil and some debris from the piston head. More pics of internal carnage to follow in next post.
right there's the reason i never run dual plane intakes anymore, had a buddy lose a cylinder then it transfered thru the intake over to the other bank. sorry to hear bout your trouble man, shitty time of yr to happen:)sphss
 

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Discussion Starter · #7 ·
Hi guys, thanks for your responses and interest. I'm trying to load the rest of the photos to complete the picture, but am having much difficulty. When you see the exhaust ports and header tubes they are very white which is what had me think it went lean by reason of bad gas or intake manifold plenum leak, but from your analysis so far, fat is the word at this point. My posting skills are actually worse that my motor running skills seem to be. haha Sorry for the delay.
 

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mo balls than $cents$
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Could you elaborate on how a dual plane intake could cause this?? Also, he had a tunnel ram, correct?
i know he has a tram, i was just sayin;) a dual plane will connect 4 cylinders together on opposite banks right? well, say #1 took a shit , it may throw pieces into the intake and get sux'd into the even bank:)bulb happens alot more than peeps think.
 

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Discussion Starter · #9 · (Edited)
Agreed, rich is anything, certainly not lean.

I think more along the lines of you simply busted a valve, not lean-detonated the motor.
Now, anything can happen, but, I've seen very few folks lean-out an engine to death and break a valve from it.
Melt holes in pistons, sure, all the time, melt off ring land tops too, but the steel valves tolerate more heat than Al. pistons.

As to why the valve broke, who knows. Maybe got tight and hung up, smacked by the piston, maybe had a microscopic imperfection for a stress riser, maybe sub-surface in the alloy, maybe shock from harmonics, maybe it just broke.
Hard to think it got wet when hot and crystalized running dry header
s
Interesting point you make, previous to this trip I have been running water to the headers managed with a rex manual control valve that wouldn't completely shut off in the closed position, I always shut if off when slowing to an idle to stop/minimize water to the headers and only ran it on low flow position when cruising or haulin ass. After the race at Elsinore I decided to disconnect the water altogether because while warming the motor on the trailer the headers were dripping water a little while we were running water thruogh it with a bilge pump. That had me realize that system was jepordizing my motor. Your suggestion of crystalization of the exhaust valve due to header water certainly seems reasonable at this point Thanks for the input.
Warren
 

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right there's the reason i never run dual plane intakes anymore, had a buddy lose a cylinder then it transfered thru the intake over to the other bank. sorry to hear bout your trouble man, shitty time of yr to happen
This can occur with single plane intakes too.
I agree though, not a lean condition. Valve stuck in the guide (before the impact)?
 

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Discussion Starter · #15 ·
the last few

In your opinions, what are the chances the crank index or alignment was affected by the valve head crushing between the Eagle h-beam con. rod and the pan rail? The crank is a heavy brc forged unit. Imo at least the very least the #3&4 rods are junk, I'm just a hopin and a prayin the crank survived w/o issue, what do you guys think? It will be sent out and checked by Henry Velasko nun the less, I'm just lookin for a silver lining in this mess some how. Here's some pics of the rotater side of things.
Auto part Machine Metal


Machine Architecture Machine tool Auto part Glass


Muffler Machine Metal
 

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Discussion Starter · #16 · (Edited)
This can occur with single plane intakes too.
I agree though, not a lean condition.
Valve stuck in the guide (before the impact)?
I don't understand why all the exhaust ports and headers are so white, (except the oiled down 2) shouldn't they be more brownish or even blackish if it was running to fat? This thing never skipped a beat until it grenaded. I agree, all indicators seem quite obvious now that the exhaust valve hung up in the guide for some unclear reason at this point, I'm just hoping to understand how/why so I can prevent it in the future if at all possible. Thanks again for the input.
Warren
 

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I don't understand why all the exhaust ports and headers are so white, (except the oiled down 2) shouldn't they be more brownish or even blackish if it was running to fat? This thing never skipped a beat until it grenaded. I agree, all indicators seem quite obvious now that the exhaust valve hung up in the guide for some unclear reason at this point, I'm just hoping to understand how/why so I can prevent it in the future if at all possible. Thanks again for the input.
Warren
I am not the expert but I am thinking the leaded fuel. I know when I had the flat and ran avgas pipes looked just like that. Just my quess. :D
 

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I don't understand why all the exhaust ports and headers are so white, (except the oiled down 2) shouldn't they be more brownish or even blackish if it was running to fat? This thing never skipped a beat until it grenaded. I agree, all indicators seem quite obvious now that the exhaust valve hung up in the guide for some unclear reason at this point, I'm just hoping to understand how/why so I can prevent it in the future if at all possible. Thanks again for the input.
Warren
you can't read a set of plugs that he's cruised around on and idled a long time on.

the only way to get a good reading is to stick a fresh set of plugs in, then make a wide open pass and then click the engine off.


it probably is fat at idle or cruising speed and that is what you're seeing on the plug. that's no indication of how its running at WOT.

as for the headers, my motor runs pig rich at cruising rpms and my pipes look just like his.
 

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Discussion Starter · #19 ·
you can't read a set of plugs that he's cruised around on and idled a long time on.

the only way to get a good reading is to stick a fresh set of plugs in, then make a wide open pass and then click the engine off.


it probably is fat at idle or cruising speed and that is what you're seeing on the plug. that's no indication of how its running at WOT.

as for the headers, my motor runs pig rich at cruising rpms and my pipes look just like his.
Thanks Cyclone for the comparison example. I have learned several things in this post process one of which is that my perspective of my exhaust valve failure and subsequent motor damage was not directly caused by a lean condition or my not so brilliant:)bulb choice to use up some old gas though I'm sure that didn't necessarily help any. I guess as I pull the motor down more, especially the heads, I may find some tale tale signs of possible issues developing in other valves and #3 just "won the race" to destruction. hahaha
 

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dyno

I recommend after the repairs are done that you have the motor dynoed,
and install an EGT exhaust gas temperature guage. also I would not trust race gas octane rating that has been exposed to air longer than 30-45 days. good luck
 
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